This paper explores the processing of metrical structure in Russian, a language with free lexical stress. According to the existing theoretical accounts, not all Russian stems are specified for accent in the lexicon. The present study employs event-related potentials (ERPs) to find evidence to support the underlying distinction into accented and unaccented stem types. The results of two EEG experiments using a stress violation paradigm reveal that Russian listeners are highly sensitive to changes of metrical structure and that prosodic manipulations may impede lexical retrieval. In the first experiment, in which the stimuli were not given prior to auditory presentation, metrical violations evoked a pronounced N400 effect for all stem types, and a late positivity for one of the stem types, indicating a difference in stress processing. In the second experiment in which the stimuli were visually introduced before auditory presentation, stress shifts to the second syllable induced late positive component (LPC) indicating an ease in the evaluation of the metrical form. Overall, the present findings partially support the division into lexically specified and unspecified Russian accent types. In addition, the results show a strong correlation between the patterning of ERP components and the direction of stress shift, suggesting a trochee to be the default foot type in Russian.